The present invention relates to devices for applying lengths of pressure-sensitive adhesive-coated tape to objects such as boxes.
Examples of devices for applying adhesive coated tape are described in Collet et al U.S. Pat. No. 3,915,786, Patterson U.S. Pat. No. 3,954,550, and Deering, Jr. U.S. Pat. No. 4,238,269. Such devices are commonly used to seal boxes filled with merchandise. The boxes are driven past the device by a conveyor. Typically these devices include an application member such as a roller for supporting an end of the tape with the adhesive side disposed outwardly in a contact position such that the tape end contacts the box moving towards the tape. Upon such contact, the tape end adheres to the box. As the box moves, the box pulls the tape from the device and the application member presses the tape against the contour of the box. As the box moves past the device, the applied length of tape is severed from the supply length of tape. The tape adjacent a newly severed end with the application member is moved back to its initial contact position for contact by the next box on the conveyor.
The Collet et al U.S. Pat. No. 3,915,786 and the Patterson U.S. Pat. No. 3,954,550 describe devices that have pivotally mounted application members. The application member has one end of an arm pivotally mounted at one edge of the path of the boxes. After the leading surface of the box contacts the tape on the application member, the application member revolves about a pivot point to follow the contour of the box and presses the tape sequentially against the leading surface of the box, then along a top surface of the box defined by adjacent edge portions of abutted cover flaps of the box, and then over a trailing surface of the box. The force applied by the leading surface of the box to move the application member across its leading surface increases significantly as the application member approaches the edge of the box. This force can become large enough to push in the leading wall of the box under the box's two cover flaps, particularly for lightly constructed boxes.
The Deering, Jr. U.S. Pat. No. 4,238,269 describes a linearly retractable application member that applies tape at a uniform pressure solving the problem caused by the increasing forces of the pivotally mounted application member. The linearly retracted bolt application member is moved by movement of the box along a generally linear path from a contact position at which the application member is contacted by a leading surface of the box to a second position at which it will be held against one side of the box as the box moves passed the member. The force applied by the leading surface of the box to move the application member to its second position is essentially uniform as the application member traverses the leading surface of the box thereby avoiding pushing in the front wall of the box.
However, even with the uniform pressure applied by a linearly retractable application member, problems have occurred with long, large, or thin-walled constructed boxes or boxes with contents that do not provide support to the edge portion of the cover flaps that are being taped. In both cases, the cover flaps cannot support the force applied by a pivotally mounted application member or a linearly retractable application member. As the application member leaves the leading edge of the box and approaches the mid-section of the box, the force spreads the cover flaps apart from each other. The result is that the tape is not applied properly. In some instances, the application member spreads the cover flap so far apart that the application member breaks through into the interior of the box. On some occasions, the application member breaks through sufficiently into the interior of the box to set off the tape severing mechanism, prematurely severing the tape.